Bring a large pot of water to a boil. Add one tablespoon of salt, drizzle a little bit of extra virgin olive oil and the pasta and cook according to the directions on the package. Set aside 1-½ cups of the pasta cooking water before you drain the pasta.
Meanwhile, heat 2 tablespoons of extra olive oil in a large wide pot over high heat. Add the mushrooms, toss well and saute for about 5 minutes over high heat, then turn down to medium heat as the mushrooms begin to develop some color and the water from them evaporates. Remove the mushrooms from the pan. Heat the remaining 2 tablespoons of olive oil. Add the onions to the pan and toss well. Saute another 10 minutes until the onions are golden brown. Add the garlic and cook for another minute.
Add the mushrooms to the pan and stir in the paprika, chicken bouillon, and ground black pepper. Reduce the heat to medium. Add the pasta, ¾ cup cooking water, sour cream, and vinegar to the mushroom-onion mixture. Toss until the pasta is well coated and slightly saucy, gradually adding the remaining cooking water as needed.
Add about half each of the cilantro, green onion, and shredded Parmesan cheese to the pasta and toss; taste and season with salt and pepper, if necessary. Divide among bowls and top with the remaining cilantro, green onion, and shredded Parmesan. Enjoy our Delicious Creamy Pasta with Mushrooms and Caramelized Onions. Enjoy!